Physics :)

(all)
-all the forces acting on an object are balanced
-the sum of the positive horizontal forces on an object equals the sum of the negative horizontal forces
-the net force on the object is zero
-the sum of the upward forces equals the sum of the downward forces
Equilibrium occurs when
(A and B)
-it oscillates back and forth between the two banks
-moves in the direction of the resultant force on it
A barge is being pulled along a canal by two ropes that make equal angles with the direction in which the barge points. Assuming the two pulls on the barge are equal, in what direction does the barge move?
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more than half the tire’s weight
A clothesline is stretched between two trees. A tire hangs in the middle of the line and the two halves of the line make equal angles with the horizontal. The tension in the line is ..
only magnitude
A scalar quantity has
it is dynamic equilibrium
You are helping your aunt move a piano on wheels from one room to another. When you push the piano horizontally, it moves at constant speed. What can you say about the piano?
to nearly its original height
Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?
opposite to an object’s motion
Friction is a force that always acts
(all of the above)
-will continue moving at the same velocity unless an outside force acts on it
-will continue moving in a straight line unless an outside force acts on it
-that is not moving will never move unless a force acts on it
-at rest will remain at rest unless acted by an outside force
The law of inertia states that an object
zero, since no force is necessary to keep it moving
After a cannonball is fired into friction-less space, the amount of force needed to keep it going equals
the milk carton has inertia
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
zero
The force required to maintain an object at a constant speed in free space is equal to
inertia
One object has twice as much mass as another object. The first object also has twice as much
less
Compared to its weight on Earth, a 10-kg object on the moon will weigh
the same
Compared to its mass on Earth, the mass of a 10-kg object on the moon is
neither – they both have the same mass
Which has more mass, a kilogram of feathers or a kilogram of iron?
100 N
A bag of canned goods has a mass of 10.0 kilograms and a weight of
Newton’s first law holds that your body moves along with Earth because it is not compelled to change its motion by an unbalanced force.
You and a friend are jumping on a trampoline. Why does Earth, which is rapidly orbiting around the sun, not move under your feet when you jump?
False
T or F. Mass is a vector quantity.
True
T or F. Force is a vector quantity.
False
T or F. If a hockey puck were to slide on a perfectly friction-less surface, it will eventually slow down because of its inertia.
False
T or F. If you were to slide a hockey puck across a friction-less ice rink, there must be a horizontal force on it to keep it in motion.
False (it’s kg)
T or F. The SI unit of mass is the newton.
True (same ass, different wait)
T or F. An astronaut has the same mass on Earth as in space.
True
T or F. The reason a penny thrown straight up inside an airplane will come back to your hand is that you, the air inside the plane, and the penny are all moving at the same horizontal velocity.
IV
(picture of rainbow shape) The vertical speed of the ball at point II is the same as its vertical speed at point
They are all the same
(picture of rainbow shape) When is the horizontal velocity the greatest?
III
(picture of rainbow shape) When is the vertical velocity zero?
both magnitude and direction
A vector quantity has
(all of the above)
-the direction of the arrow shows the direction of motion
-the length of the arrow represents the speed
-the length of the arrow is drawn to a suitable scale
When representing velocity as a vector,
the vertical component of its velocity
The horizontal component of a projectile’s velocity is independent of
neither. they both hit the ground at the same time.
At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
entirely horizontal
A ball is thrown into the air at some angle. At the very top of the ball’s path, its velocity is
g downward
An object is dropped and falls freely to the ground with an acceleration of g (-10m/s/s)/ If it is thrown upward at an angle instead, its acceleration would be
the same as when it was at the top of its path
After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)
more
An airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is
230 km/h
Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind (going in the same direction as the plane). How fast does the plane’s shadow move across the ground?
20 m/s
A ball is thrown straight upward with an initial vertical velocity of 20 m/s. Ideally (no air resistance), the ball will return to the thrower’s hand with a speed of
instantaneous speed
When you look at the speedometer in a moving car, you can see the car’s
c (right most top)
(picture of curve bottom left to top right) At what point is the instantaneous velocity largest?
positive acceleration (speeding up)
(picture of curve bottom left to top right) The graph above illustrates an object moving with
velocity of an object per unit of time
Acceleration is defined as the CHANGE in
Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour. Which of the following is NOT true?
velocity increases
As an object falls freely in a vacuum, its
acceleration
In the absence of air resistance, objects fall at constant
get farther apart
Consider drops of water leaking from a water faucet. As the drops fall for a longer time they
both will land at the same time
If you drop a feather and a coin on the moon (from the same height and same time), which will land first?
Swimmer B passes swimmer A after 40 seconds has passed since they began the race
Given below is the graph representing the position-time graphs of two swimmers (A and B), swimming in a pool along a straight line. Both the swimmers start from two different positions. Use the graph to find when and where swimmer B passes swimmer A.
True
T or F. A single vector can be replaced by two vectors in the x- and y-directions that are a right angles to each other.
True
T or F. A The vertical component of velocity in projectile motion is identical to the velocity component of free fall.
True
T or F. The rate at which velocity changes with time is called acceleration.
True
T or F. Velocity is different from speed in that velocity is speed in a given direction.
True
T or F. The length of a vector represents its magnitude.
30 N
A 15-N force and a 45-N force act on an object in opposite directions (180 degrees). What is the net force on the object?
straight down, even if the person is standing on an incline
The weight of a person can be represented by a vector that acts
forces
Accelerations are produced by
(all of the above)
-inversely proportional to the mass of the object
-directly proportional to the magnitude of the net force
-in the same direction as the net force
The acceleration produced by a net force on an object is
0 m/s^2
When an object reaches terminal velocity its acceleration
25 N
Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is
0 N
A book weighs 4 N. When held at rest in your hands, the net force on the book is
1 N
An apple weighs 1 N. The net force on the apple when it is in free fall is
acceleration
An object has a constant mass. A constant force on the object produces constant
with 10 times as much force
A push on a 1-kg brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push
continues at the speed it had when it encountered the second force
Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle
force per area
Pressure is defined as
a woman standing in high-heel shoes
Which of the following would exert the most pressure on the ground?
steel ball
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. They land at the same time. Which ball has the greater force of gravity acting on it?
They both have the same acceleration
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration due to gravity?
remains the same
As a care package falls from a high-flying stationary helicopter, its velocity increases and its acceleration
250 N
If you pull horizontally on a desk with a force of 150 N and the desk doesnt move, the friction force must be 150 N. Now if you pull with 250 N so the desk slides at constant velocity, the friction force is
decreases
When the angle of an incline with a block resting on it increases, the normal support force
is 2300 N
A karate chop delivers a blow of 2300 N to a board that breaks. The force that acts on the hand during this feat
decreases
Consider a ball rolling down the decreasing slope inside a semicircular bowl. As the ball rolls from the rim downward toward the bottom, its acceleration
it doubles
If the force acting on a cart doubles, what happens to the cart’s
decrease the pressure on the ice
You are on a frozen pond, and the ice starts to crack. If you lie down on the ice and begin to crawl, this will
1/10 times that of the car
If a truck has ten times the mass of a car and the two vehicles are pushed with an equal force, you would expect the acceleration of the truck to be
always true
Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.
on the nail and also on the hammer
A high school student hits a nail with a hammer. During the collision, there is a force
The force of the ball against the bat
A player hits the ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?
440 N
A person is attracted towards the center of Earth by a 440-N gravitational force. The force with which Earth is attracted toward the person is
the same
An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is
larger
An unfortunate bug splatters against the windshield of a moving car. Compared to the acceleration of the car, the acceleration of the bug is
yes
Two people pull on a rope in a tug-of-war. Each pulls with 400 N of force. Is the tension in the rope 400 N?
down arrow
(picture of circle with circle with circle) The horizontal turntable shown above rotates at a constant rate. As viewed from above a coin on the turntable moves counterclockwise in a circle as shown. Which of the following vectors best represents the direction of the frictional force exerted on the coin by the turntable when the coin is in the position shown?
the outside horse
Which has greater linear speed (tangental), a horse near the outside rail of a merry-go-round or a horse near the inside rail?
neither
Which has greater rotational speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?
inward toward the center of the washing machine
What is the direction of the force that acts on clothes in the spin cycle of a washing machine?
there is an inward force of the string acting on the can
A tin can whirled on the end of a string moves in a circle because
fly off in a straight line, tangent to its circular path.
If you whirl a tin can on the end of a string and the string suddenly breaks, the can will
is directed toward the center of the curve
A car travels in a circle with constant speed. The net force on the car
*When a racecar rounds a banked track, the centripetal force needed comes not from friction, but from the
*Earth rotates and revolves through space. Earth rotates about the ____, which is an ____ axis. Earth revolves about the _____, which is an _____ axis.
mass times its velocity
The momentum of an object is defined as the object’s
the large truck
Which has more momentum, a large mass truck moving at 30 miles per hour or a small mass truck moving at 30 miles per hour?
twice as much momentum
Compared to a sports car moving 30 miles per hour, the same sports car moving at 60 miles per hour has
(all of the above) it is accelerating, there is a force acting on it, its velocity is changing
If the momentum of an object changes and its mass remains constant
impulse acting on it
The momentum change of an object is equal to the
(all of the above)
-follow through when hitting the ball (increasing the time of contact with the ball)
-swing as hard as possible (increasing the force)
In order to increase the final momentum of a golf ball, we could
increase the time of impact in a collision, decreasing the impact force
The reason padded dashboards are used in cars is that they
larger
A cannonball is fired from a cannon. Compared to the force on the ball, the force on the cannon is
*A cannonball is fired from a cannon. Compared to the impulse (change in momentum) on the ball, the impulse on the cannon is
there is no net external force acting on the system
Momentum of a system is conserved only when
doubled
A freight train rolls along a track with considerable momentum. If t were to roll at the same speed but had twice as much mass, its momentum would be
cannon has far more mass than the cannonball
A cannon recoils from launching a cannonball. The speed of the cannon’s recoil is small because the
momentum
Two objects, A and B, have the same size and shape, but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, but A has a higher
the time of impact is increased
In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball’s motion. Doing this reduces the force of impact on the player’s hand principally because
(all of the above)
-less stopping distance
-more momentum
-more mass
A car traveling along the highway needs a certain amount of force exerted on it to stop. More stopping force may be required when the car has
the mass of the cannonball equals the mass of the cannon
A cannon fires a cannonball. The speed of the cannonball will be the same as the speed of the recoiling cannon if
less than 10 times
When you jump off a step, you usually bend your knees as you reach the ground. By doing this, the time of the impact is about 10 times more what it would be in a stiff-legged landing, and the average force on your body is reduced by
smaller
A moving freight car runs into an identical car at rest on the track. The cars couple together. Compared to the velocity of the first car before the collision, the velocity of the combined cars after the collision is
impulse
A cannonball shot from a long-barrel cannon travels faster than one shot from a short-barrel cannon because the cannonball recieves a greater
True
T or F. Momentum is inertia in motion.
False
T or F. A child on a merry-go-round rotates around the merry-go-round’s axis.
250 N
A girl whose weight is 500 N hangs from the the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?
30N
A 15-N force and a 45-N force act on an object in opposite directions, but in a straight line. What is the net force on the object?
C (both guys are on same left side of scaffold)
Burl and Paul stand on their sign-painting scaffold. Which letter in the diagram below shows the greatest tension in the LEFT rope?
True
T or F. Force is a vector quantity, which means it includes magnitude and direction.
5 km/hr/sec
Suppose a car is moving in a straight line and steadily increases its velocity. During the first second, the car moves from 35 km/hr to 40 km/hr. During the next second it moves from 40 km/hr to 45 km/hr. What is the car’s average acceleration?
60 km/hr
Suppose you take a trip to Grandma’s house that takes 3 hours. Her house is approximately 180 km from your home. What is your average speed during the trip?
Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 km/hr. Which of the following is NOT true?
letters a and b only
Which of the following units can be used to describe speed and/or velocity?
0 km/sec; 30 km/sec
A pencil lies stationary on your desk. If the Earth is moving around the sun at a speed of 30 km/sec, how fast is the pencil moving relative to the desk? How fast is the pencil moving relative to the sun?
the same or, g (-10 m/s/s)
An object is dropped and falls freely (i.e. not influenced by friction or wind resistance) to the ground with an acceleration of g. If it is thrown upward instead, its acceleration would be
10 m/s
During each second of free fall an object picks up
acceleration
The slope of a speed-versus-time graph represents
is not acted on by any horizontal forces
A projectile is fired horizontally in a vacuum. The projecticle maintains its horizontal component of speed because it
true
T or F. A single vector (or resultant) can be replaced by two component vectors in the x- and y-directions that are at right angles to each other.
entirely horizontal
A ball is thrown into the air at some angle. At the very top of the ball’s path, its velocity is
zero
A book weighs 4 N. When held at rest in your hands, the net force on the book is
acceleration
An object has a constant mass. A constant force on the object produces constant
half as much
A force of 3 N accelerates a mass of 3 kg at the rate of 1 m/s2. The acceleration of a mass of 6 kg acted upon by the same 3 N force is
6 N
An apple weighs 6 N. The net force on the apple when it is in free fall is
it doubles
If the force acting on a cart doubles, what happens to the cart’s acceleration (as long as the cart’s mass remains the same)?
neither – they both have the same angular (rotational) speed
Which has greater angular speed (Rotational), a horse near the outside rail of a merry-go-round or a horse near the inside rail?
the moon has a sufficiently large orbital speed
Earth’s gravitational force provides the inward centripetal force to keep the moon orbiting the earth. However, the reason the moon does not fall into Earth is that _____.
twice as much momentum
Compared to a sports car moving at 30 miles per hour, the same sports car moving at 60 miles per hour has
power
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of
four times the work
If Nellie Newton pushes an object with twice the force for twice the distance, she does
watt
The unit of power is the
True
T or F. Energy is changed from one form of energy to another form with no net loss or gain.
momentum
If an object has kinetic energy, then it also MUST have
velocity
An object that has kinetic energy MUST have

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